_______________General Description

The MAX1640/MAX1641 CMOS, adjustable-output,

switch-mode current sources operate from a +5.5V to

+26V input, and are ideal for microprocessor-controlled

battery chargers. Charging current, maximum output

voltage, and pulse-trickle charge are programmed with

external resistors. Programming the off-time modifies

the switching frequency, suppressing undesirable har-

monics in noise-sensitive circuits. The MAX1640’s high-

side current sensing allows the load to connect directly

to ground, eliminating ground-potential errors. The

MAX1641 incorporates a low-side current sense.

The MAX1640/MAX1641 step-down pulse-width-modu-

lation (PWM) controllers use an external P-channel

MOSFET switch and an optional, external N-channel

MOSFET synchronous rectifier for increased efficiency.

An internal low-dropout linear regulator provides power

for the internal reference and circuitry as well as the

gate drive for the N-channel synchronous rectifier.

The MAX1640/MAX1641 are available in space-saving,

16-pin narrow QSOP packages.

________________________Applications

Battery-Powered Equipment

Laptop, Notebook, and Palmtop Computers

Handy Terminals

Portable Consumer Products

Cordless Phones

Cellular Phones

PCS Phones

Backup Battery Charger

____________________________Features

o 95% Efficiency

o +5.5V to +26V Input Supply Range

o 2V to 24V Adjustable-Output Voltage Range

o 100% Maximum Duty Cycle (Low Dropout)

o Up to 500kHz PWM Operation

o Optional Synchronous Rectifier

o 16-Pin QSOP Package

o Current-Sense Accuracy: 2% (MAX1641)

5.3% (MAX1640)

Adjustable-Output, Switch-Mode

Current Sources with Synchronous Rectifier

________________________________________________________________

Maxim Integrated Products

1

__________________Pin Configuration

16

15

14

13

12

11

10

9

1

2

3

4

5

6

7

8

LDOL

IN

LDOH

PDRV

NDRV

PGND

CS+

CS-

GND

TOP VIEW

MAX1640

MAX1641

QSOP

TOFF

D1

REF

D0

CC

SET

TERM

19-1245; Rev 0; 7/97

PART

MAX1640C/D

MAX1640EEE

MAX1641C/D

0°C to +70°C

-40°C to +85°C

0°C to +70°C

TEMP. RANGE

PIN-PACKAGE

Dice*

16 QSOP

Dice*

______________Ordering Information

*

MAX1641EEE

-40°C to +85°C

16 QSOP

IN

LDOH

PDRV

NDRV

P

PGND

CS+

CS-

TERM

LDOL

GND

OUT

D0

D1

TOFF

REF

SET

CC

MAX1640

__________Typical Operating Circuit

EVALUATION

KIT

AVAILABLE

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.

For small orders, phone 408-737-7600 ext. 3468.